Data from: Functional traits for carbon access in macrophytes

Understanding functional trait distributions among organisms can inform impacts on and responses to environmental change. In marine systems, only 1% of dissolved inorganic carbon in seawater exists as CO2. Thus the majority of marine macrophytes not only passively access CO2 for photosynthesis, but also actively transport CO2 and the more common bicarbonate (HCO3-, 92% of seawater dissolved inorganic carbon) into their cells. Because species with these carbon concentrating mechanisms (CCMs) are non-randomly distributed in ecosystems, we ask whether there is a phylogenetic pattern to the distribution of CCMs among algal species. To determine macrophyte traits that influence carbon uptake, we assessed 40 common macrophyte species from the rocky intertidal community of the Northeast Pacific Ocean to a) query whether macrophytes have a CCM and b) determine the evolutionary history of CCMs, using ancestral state reconstructions and stochastic character mapping based on previously published data. Thirty-two species not only depleted CO2, but also concentrated and depleted HCO3-, indicative of a CCM. While analysis of CCMs as a continuous trait in 30 families within Phylum Rhodophyta showed a significant phylogenetic signal under a Brownian motion model, analysis of CCMs as a discrete trait (presence or absence) indicated that red algal families are more divergent than expected in their CCM presence or absence; CCMs are a labile trait within the Rhodophyta. In contrast, CCMs were present in each of 18 Ochrophyta families surveyed, indicating that CCMs are highly conserved in the brown algae. The trait of CCM presence or absence was largely conserved within Families. Fifteen of 23 species tested also changed the seawater buffering capacity, or Total Alkalinity (TA), shifting DIC composition towards increasing concentrations of HCO3- and CO2 for photosynthesis. Manipulating the external TA of the local environment may influence carbon availability in boundary layers and areas of low water mixing, offering an additional mechanism to increase CO2 availability.解析生物的功能性状分布格局，可为探究生物对环境变化的响应及其施加的影响提供科学依据。在海洋系统中，海水中仅1%的溶解无机碳（dissolved inorganic carbon, DIC）以二氧化碳（CO₂）形式存在。因此，绝大多数海洋大型植物不仅通过被动途径获取光合作用所需的CO₂，还会主动将CO₂及占海水溶解无机碳总量92%的碳酸氢根（HCO₃⁻）转运至细胞内。由于具备碳浓缩机制（carbon concentrating mechanisms, CCMs）的物种在生态系统中的分布并非随机，本研究旨在探究藻类物种中CCMs的分布是否存在系统发育格局。为明确影响碳摄取过程的大型植物性状，本研究基于已发表的数据，采用祖先状态重建与随机特征映射方法，对采集自东北太平洋潮间带岩礁群落的40种常见海洋大型植物开展了两项分析：一是查询该类植物是否具备CCMs，二是解析CCMs的演化历史。其中32个物种不仅可消耗CO₂，还能富集并消耗HCO₃⁻，这表明其具备CCMs。尽管将红藻门（Phylum Rhodophyta）内30个科的CCMs作为连续性状进行分析时，布朗运动模型下检测到显著的系统发育信号，但将CCMs作为有/无的离散性状分析时，结果显示红藻类各科在CCMs的有无上较预期更为分化；可见CCMs在红藻门中属于易变性状。与之形成对比的是，本次调研的18个隶属于不等鞭毛门（Ochrophyta）的科均检测到CCMs的存在，表明CCMs在褐藻类群中高度保守。CCMs的有无这一性状在各科内整体上较为保守。本次测试的23个物种中，有15个还能改变海水缓冲能力，即总碱度（Total Alkalinity, TA），进而改变溶解无机碳的组成，使HCO₃⁻与CO₂的浓度升高以满足光合作用需求。调控局域环境的外源总碱度，可影响边界层及低水混合区域的碳可利用性，这为提升CO₂的可利用性提供了一种额外机制。